1. Field of the Invention
This invention generally relates to a bicycle crank assembly. More specifically, the present invention relates to a bicycle crank assembly with an axle coupling structure for coupling a crank axle to a crank arm.
2. Background Information
A bicycle crank arm is a component for connecting a pedal to a crank axle. In the case of a right crank arm, one or more chain rings is attached to the crank arm for transmitting a pedaling force from the pedal to a chain. The crank arm should have high strength in order to prevent damage or deformation despite the crank arm being repeatedly subjected to loads from the pedal, and high rigidity in order to prevent deformation or flexing when the pedal is depressed. The crank arm is preferably also designed to be as lightweight as possible in order to reduce the weight of the entire bicycle. Often, a spline type connection is provided for coupling the crank axle to the crank arm. In this way, the pedaling force transmitted from the crank arm to the crank axle via the spline type connection between the crank arm and the crank axle. The spline type connection is subjected to a large stress during a power portion of the pedaling motion.